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Date: Mon, 31 Oct 2016 22:54:54 +0100
From: Joerg Roedel <jroedel@suse.de>
To: Martin Kepplinger <martink@posteo.de>
Cc: Linux kernel <linux-kernel@vger.kernel.org>,
        torvalds@linux-foundation.org, daniel.vetter@intel.com,
        jani.nikula@linux.intel.com
Subject: Re: [BUG][REGRESSION] mangled display since -rc1
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On Mon, Oct 31, 2016 at 09:44:51PM +0100, Martin Kepplinger wrote:
> This is one machine booting a bad kernel. I could provide another
> example later this week.

You have an Intel system without any IOMMU (enabled), otherwise you
would have a DMAR-ACPI table, but there is none:

> [    0.000000] ACPI: RSDP 0x00000000000FE020 000024 (v02 ACRSYS)
> [    0.000000] ACPI: XSDT 0x00000000A6FFE210 00008C (v01 ACRSYS ACRPRDCT 00000001      01000013)
> [    0.000000] ACPI: FACP 0x00000000A6FFB000 0000F4 (v04 ACRSYS ACRPRDCT 00000001 1025 00040000)
> [    0.000000] ACPI: DSDT 0x00000000A6FEC000 00B903 (v01 ACRSYS ACRPRDCT 00000000 1025 00040000)
> [    0.000000] ACPI: FACS 0x00000000A6FBB000 000040
> [    0.000000] ACPI: FACS 0x00000000A6FBB000 000040
> [    0.000000] ACPI: UEFI 0x00000000A6FFD000 000236 (v01 ACRSYS ACRPRDCT 00000001 1025 00040000)
> [    0.000000] ACPI: ASF! 0x00000000A6FFC000 0000A5 (v32 ACRSYS ACRPRDCT 00000001 1025 00040000)
> [    0.000000] ACPI: HPET 0x00000000A6FFA000 000038 (v01 ACRSYS ACRPRDCT 00000001 1025 00040000)
> [    0.000000] ACPI: APIC 0x00000000A6FF9000 00008C (v02 ACRSYS ACRPRDCT 00000001 1025 00040000)
> [    0.000000] ACPI: MCFG 0x00000000A6FF8000 00003C (v01 ACRSYS ACRPRDCT 00000001 1025 00040000)
> [    0.000000] ACPI: SLIC 0x00000000A6FEB000 000176 (v01 ACRSYS ACRPRDCT 00000001 1025 00040000)
> [    0.000000] ACPI: SSDT 0x00000000A6FEA000 0006FE (v01 ACRSYS ACRPRDCT 00001000 1025 00040000)
> [    0.000000] ACPI: BOOT 0x00000000A6FE8000 000028 (v01 ACRSYS ACRPRDCT 00000001 1025 00040000)
> [    0.000000] ACPI: ASPT 0x00000000A6FE3000 000034 (v07 ACRSYS ACRPRDCT 00000001 1025 00040000)
> [    0.000000] ACPI: FPDT 0x00000000A6FE1000 000044 (v01 ACRSYS ACRPRDCT 00000001 1025 00040000)
> [    0.000000] ACPI: SSDT 0x00000000A6FE0000 00079A (v01 ACRSYS ACRPRDCT 00003000 1025 00040000)
> [    0.000000] ACPI: SSDT 0x00000000A6FDF000 000A92 (v01 ACRSYS ACRPRDCT 00003000 1025 00040000)

So it is pretty unlikely that any change in IOMMU code causes your
issue. Not sure why your bisecting ended up there. You also have an
Intel GPU in the system:

> 00:02.0 VGA compatible controller: Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller (rev 09) (prog-if 00 [VGA controller])
> 	Subsystem: Acer Incorporated [ALI] Device 0748
> 	Flags: bus master, fast devsel, latency 0, IRQ 28
> 	Memory at c0000000 (64-bit, non-prefetchable) [size=4M]
> 	Memory at b0000000 (64-bit, prefetchable) [size=256M]
> 	I/O ports at 2000 [size=64]
> 	[virtual] Expansion ROM at 000c0000 [disabled] [size=128K]
> 	Capabilities: <access denied>
> 	Kernel driver in use: i915

My best guess is that some changes in the i915 driver cause your issue,
I add the maintainers of i915 to the cc-list, maybe they have an idea.


	Joerg